Pressure-regulating valves for hydraulic systems



July 1956 D. L. SPENCER 2,756,771

PRESSURE-REGULATING VALVES FOR HYDRAULIC SYSTEMS Filed May 21, 1952 M/l ENTOE fii/v/vfs L. SFA'NCER ATTOI? Ex PRESSURE-REGULATING VALVES FOR HYDRAULIC SYSTEMS Dennis Lincoln Spencer, West Twyford, London, England, assignor, by mesne assignments, to The Sperry Gyroscope Company, Limited, Brentford, England, a British company Application May 21, 1952, Serial No. 289,101

Claims priority, application Great Britain May '25, 1951 4 Claims. (Cl. 137-494) The present invention relates to hydraulic installations for supplying fluid at an operating pressure to hydraulic utilisation apparatus such as a reversible hydraulic motor used as the servo-motor of an automatic control system or servo mechanism, and, in particular, to installations of the Ikind in which the pressure-fluid is passed from the source to the utilisation apparatus through a pressure-regulating valve that includes a variable throttling construction between its inlet and its outlet, the outlet being connected to the utilisation apparatusto serve as the source of pressurefluid for that apparatus, so that, if the valve setting is adjusted to open the throttling constriction, the output pressure applied to the utilisation apparatus rises, while, if the valve setting is adjusted to close the throttling constriction, the output pressure applied to the utilisation apparatus falls. In order to serve as pressure-regulating devices such valves are arranged to be subjected to a closing force that tends to close the valve and throttle the supply of fluid, this closing force being exerted under the influence of the utilization pressure in the fluid in the outlet side of the valve.

According to the invention there is provided a regulating valve for regulating the pressure at which pressure fluid is passed to hydraulic utilisation apparatus and adapted to exercise a regulating action on the pressure of the fluid in an outlet channel leading from it to the utilisation apparatus by virtue of the fact that a force is applied automatically to the movable element of the valve in dependence on the pressure developed in the outlet channel, this force operating degeneratively in the direction to close the valve and thus reduce the outlet pressure, character'ised by the fact that the said closing force is applied to the movable element of the valve by reason of a resilient coupling (for example a spring) between the movable element of the valve and an auxiliary movable member, the closing force being developed in consequence of a hydraulic thrust applied to the auxiliary movable member by fluid at or near the pressure obtaining in the outlet channel of the valve; and characterised also in that the movements of the auxiliary movable element are hydraulically damped.

The use of the auxiliary damped movable element, through which the closing force is applied according to the invention so stabilizes the operation of the valve that it enables valves of the poppet or ball type to be used as regulating valves. Since those are substantially free from a tendency to stick or to become hydraulically locked, it is preferred to use valves of this type in embodiments of the invention, more especially if the hydraulic installation in which the regulating valve is used is one using highpressure fluid.

In order that the invention may be more clearly understood and readily carried into practice, a specific example thereof will now be described by way of example with reference to the accompanying drawing, the single figure of which shows a preferred embodiment of the invention as applied to a poppet type of regulating valve.

Referring to the drawing, pressure fluid is supplied from bias the valve towards the closed position.

2,756,771 Patented July 31, 1 956 an inlet channel 1, by way of an orifice controlled by a poppet valve 2 to an outlet channel 3 which leads to hydraulic utilisation apparatus (not shown). A feedback channel 4 leads from the outlet channel 3 to a 5 cylinder 5 in which is movable a piston 6. On a common shaft with the piston 6, is a damping piston 7 which is movable in a cylinder which is subjected to the outlet fluid pressure. A helical spring 8 is positioned between one face of the damping piston 7 and the poppet valve 2 to The faces of the damping piston 7 are connected by holes 9 of such small bore that viscous damping forces are produced Whenever hydraulic fluid flows from one face of the piston to the other through the holes. The arrangement is such that the damping piston 7 cannot move in its cylinder without the passage of hydraulic fluid from the outlet channel 3 to the chamber 10 on the other side of the piston or from the chamber 10 to the outlet channel 3.

In operation, pressure fluid in the inlet channel 1 produces a force on the poppet valve 2. causing it to open and allow the fluid to enter the channel 3. The pressure in the outlet channel 3 is regulated in accordance with the pressure drop caused by flow through the valve 2. Fluid at a pressure at or near that in the channel 3 is introduced into cylinder 5 by way of the feed-back channel 4. The

pressure of the fluid in cylinder 5 urges the piston 6 and hence the piston 7 against the spring 8 which transmits the force to the poppet valve 2 tending to close it. A balanced position is reached when the inlet pressure of the fluid acting on the poppet valve 2 is balanced by the force transmitted by the spring 8.

Due to various causes, the auxiliary movable member consisting of the pistons 6 and 7 tends to be unstable in its cylinder and may cause sudden undesirable changes in the pressure in the outlet channel 3 and according to the invention, by virtue of the holes 9 in the damping piston 7 and the fact that the piston 7 cannot move without fluid flowing through these holes, sudden movement of the auxiliary movable member is prevented and the valve is rendered substantially stable.

Although the invention has been illustrated as applied to a poppet type of valve it will be clear that it is not limited to such valves, but may also be applied to piston type valves. In such a case, the spring 8 would bear at its lower end on the top face of the piston comprising the movable element of the valve.

I claim:

1. In a regulating valve for automatically regulating the pressure at which pressure fluid is passed from an inlet :to an outlet, a housing having first and second cylindrical chambers separated by a partition having a central opening, first and second piston-like'elements slidably disposed respectively in said first and second chambers and connected in back-to-back relation by a piston rod, said piston rod being slidably fitted in said central opening, the second .piston-like element having at least one bleeder passage therethrough for permitting fluid to pass therethrough in both directions for damping purposes, the rod-less sides of both piston-like elements being in continuous communication with said outlet while the rod side of said first piston-like element is in continuous communication with .the atmosphere, a movable closure member operable in ;one direction to open and establish communication be- ,tWeen said inlet and outlet and operable in the other direc- 5 tion to cut off such communication, said closure member for attaining a balanced condition corresponding to a given outlet pressure until a variation of said pressure occurs, whereupon said closure member tends to move in a direction to restore said pressure.

2. A self-adjusting fluid pressure valve capable of exer cising regulating action on fluid being passed to a hydraulic load comprising, a housing having a plurality of chambers aligned along a common axis, a regulating valve element oriented for motion along said axis adjacent a fluid port, a fluid inlet communicating with one sid of said port, a fluid outlet communicating with the oth s said port to lead fluid released by said valve elem hydraulic load, a plurality of pistons each slidably disposed in respective ones of said chambers, means interconnecting said pistons to cause them to move in unison in their respective chambers, resilient coupling in necting said valve element to one of said pistons a ing a continuous force on said valve element in a dirtto close said port, and a fluid feedback channel connecting said fluid outlet to one of said chambers at a point thereof to cause a port closing pressure against the piston therein dependent upon an increase of fluid pressure in outlet, said fluid outlet communicating with another of said chambers to exert a pressure against the piston therein in a direction opposite to the effect of the aforesaid pressure caused by said feedback channel, said last-mentioned piston having a bleeder opening between opposite faces thereof to produce viscous damping upon passage of fluid therethrough.

3. A valve as defined in claim 2 wherein the number of chambers are two, said valve element being a poppet valve, said resilient means comprising a spring member connected at one end to the outlet side of said valve element, said resilient means connected at the other end to the face nearer said valve element of the piston next adjacent to said port, said feedback channel being connected to the distant chamber to cause pressure against the piston face remote from said port.

4. A self-adjusting fluid pressure valve capable of exercising regulating action on fluid being passed to a hydraulic load comprising, a plurality of pistons slidably disposed in respective chambers therefor, means interconnecting said pistons to cause same to move in unison, a fluid inlet, a fluid outlet communicating with said inlet by means of a port, a regulating valve element adapted to open and close said port, a resilient coupling means connecting said valve element to one of said pistons and urging a continuous closing force on said valve element, and a fluid feedback channel connecting said fluid outlet to one of said chambers to cause a pressure against the piston therein dependent upon the magnitude and sense of the fluid pressure in said outlet, said fluid outlet communicating with another of said chambers to exert a pressure against the piston therein in direction opposite to the eifect of the aforesaid pressure caused by said feedback channel, the last-mentioned of said pistons having hydraulic damping means so constructed and arranged as to damp sliding movement of said pistons in their respective chambers.

References Cited in the file of this patent UNITED STATES PATENTS 913,650 Senter Feb. 23, 1909 962,736 Bice June 28, 1910 1,531,146 Skortz Mar. 24, 1925 1,733,528 Davis Oct. 29, 1929 2,027,762 Becker Ian. 14, 1936 2,410,375 Wright Oct. 29, 1946 2,639,693 Miller May 26, 1953 

